The present invention relates to a power abnormality circuit, and especially to circuit for indicating abnormality of a three-mode surge absorber of a public electric power and a multiple-end fuse. Furthermore, the present invention provides a multiple-end fuse which is used to the circuit for indicating abnormality of a three-mode surge absorber of a public electric power.
The general power receptacle for surge protection use metal oxide varistors or other transient/surge absorbers for suppressing surge wave. These elements will heat while absorbing surge wave, even a large surge wave may induce a short circuit. Therefore, temperature fuses or current fuses are used to prevent abnormality.
In general, the breakage of fuses is used to determine the abnormality of a surge protection indicator. However, in order to prevent the leakage current to the ground, in general, the indicator only displays the condition of the input ends of line-neutral mode while the conditions of line-ground mode and neutral-ground mode are not displayed.
Referring to FIG. 1, a circuit for indicating abnormality of a surge absorber is illustrated, which includes two surge absorbing devices 10 and 30 and an abnormal indication circuit 20. The L-N ends in the three-mode in public power supply is connected to the surge absorbing device 10 in series. The surge absorbing device 30 is serially connected between the L-G and N-G ends. The surge absorbing device 10 has a two-end temperature sensing fuse 101 capable of severing from a temperature of 139xc2x0 C. and a metal oxide vairstor 102. When the metal oxide vairstor 102 has abnormality, it will heat gradually. Since it tightly presses against the two-end temperature sensing fuse 102, the metal oxide vairstor 102 will heat and finally burn off the two-end temperature sensing fuse 101 so that the surge protection indicator 202 will extinguish due to no current flowing therethrough.
The surge absorbing device 30 has two metal oxide vairstors 301 and 302 and a two-end temperature sensing fuse 303 capable of severing from a temperature of 139xc2x0 C. When the metal oxide vairstor 301 has abnormality, it will heat gradually. Since it tightly presses against the two-end temperature sensing fuse 303, the metal oxide vairstor 301 will heat and finally burn off the two-end temperature sensing fuse 303, but the two-end temperature sensing fuse 101 does not break off so that the surge protection indicator 202 will not extinguish. Namely, the fault of the surge absorbing device 30 of the L-G ends can not be detected. Furthermore, When the metal oxide vairstor 302 has abnormality, it will heat gradually. Since it tightly presses against the two-end temperature sensing fuse 303, the metal oxide vairstor 302 will heat and finally burn-cut the two-end temperature sensing fuse 303, but the two-end temperature sensing fuse 101 does not burn-cut so that the surge protection indicator 202 will not extinguish. Namely, the fault of the surge absorbing device 30 of the N-G ends can not be detected.
Accordingly, the primary object of the present invention is to provide a circuit for indicating abnormality of a three-mode surge absorber and a multiple-end fuse.
Another object of the present invention is to provide a circuit for displaying abnormality of a three-mode surge absorber of a public electric power, in which a current sufficient to cut off a third end flows through a first and a second end of a two-end fuse and at the same time, the third end is cut off so that the third end is isolated from the first and second ends completely.
To achieve above objects, the present invention provides a circuit for indicating abnormality of a three-mode surge absorber of a public electric power. The circuit is serially connected between the input end and output end of a public electric power supply for indicating the abnormality of a three-mode surge absorbing device of a public power supply so as to provide an obvious indication to the users. The circuit for indicating abnormality of a three-mode surge absorber of a public electric power of the present invention includes a first surge absorbing device coupled to the line input end and the neutral input end for absorbing a surge between the line input end and the neutral input end; a first three-end fuse coupled to the first surge absorbing device and the line input end for preventing abnormality of parts; an abnormal indication circuit coupled to the first three-end fuse for indicating the abnormality of three-mode in public power supply; a second surge absorbing device coupled to the abnormal indication circuit, the neutral input end and the ground input end for absorbing a surge between the neutral input end and the ground input end; and a second three-end fuse coupled to the neutral input end and the second surge absorbing device for preventing the abnormality of parts.
The present invention further provides a multiple-end fuse, wherein at least one end is added to a two-end fuse, when a current sufficient for the two-end fuse to break out flowing through a first end and a second end of the two-end fuse, a third end or other ends are cut off so that the third end or other ends are completely isolated with the first or the second end.